Microwave sensor for liquid mixture identification based on composite right left hand-zero-order resonator for sensitivity improvement

This work aims to present an improved version of the liquid mixture identification sensor, the proposed sensor is tested experimentally on mixture of water ethanol, the identification of liquid is based on the measurement of frequency displacement, and comparison with reference values of water ethanol. This device is based on metamaterial structure which is a composite right left hand (CRLH) resonator with zero-order resonator (ZOR). The CRLH in addition to its property of miniaturization effect, when combined with ZOR, the resonant frequency of various volume fraction are extended, which make the sensitivity higher. The high sensitivity of the sensor is obtained by an optimum choice of the CRLH components. The geometrical size of the sensor is 20 mm by 11 mm. It was printed on a RT/Duroid 5880 substrate with a very short testing surface area of 4 mm by 8 mm, the liquid is placed on the top side of the sensor, exactly on the CRLH structure. Three prototypes of sensors operating from 1 to 3 GHz are proposed, designed and simulated using the commercial software high-frequency structural simulator (HFSS). The main advantages of this work is first miaturization effect, second high sensitivity and finally a wide range of liquid can be tested with this sensor. To prove the working principle, ethanol with different volume fractions was adopted as a liquid under test, the obtained results present very good agreement with the literature and suggested that it is a miniaturized and high sensitive candidate (better than 1.38%) for liquid mixture identification.